[Annatar]

ZFS has defragmentation built into the very design of it!

It doesn't fragment, it actually turns all random writes into sequential ones, provided there is enough space because ZFS uses copy-on-write atomic writes:

http://constantin.glez.de/blog/2010/04/ten-ways-easily-impro...

http://everycity.co.uk/alasdair/2010/07/zfs-runs-really-slow...

now, for those of us in the Solaris / illumos / SmartOS world, this is well known and well understood. We either keep 20% free in the pool, or we turn off the defrag search algorithm. But now with the Linux crowd missing out on 11 years of experience, I see there will be lots of misunderstanding of what is actually going on, and consequently, lots of misinformation, which is unfortunate.

[gnufx]

Experienced* SunOS admins are aware of that and can still end up -- accidentally I think -- with ZFS filesystems with unacceptable performance in a state that Oracle apparently didn't understand. There was a ticket open for order months but I don't know whether it ever got resolved.

* I'm not sure how experienced, but they have Sun hardware running that's older than ZFS.